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OPA1632 Vocm pin

Per-Anders Sjöström
Prodigy 250 points
Other Parts Discussed in Thread: OPA1632

Hi!

 

OPA1632, pin 2, what is the input characteristics of this input? Can't find anything in the datasheet.

Have I understood it right: This input makes the outputs be centered around the voltage at this pin?

  • 0
    Genius 4530 points

    Hi Peranders,

    You are right. But there is a little bit more to it.

    Vocm sets the output common mode voltage, the voltage level around which the output voltage is centred.

    By default it is set to Vcc/2 where Vcc is the supply voltage, if it is required to be at the same level, then Vocm should be left unconnected.

    If you require a dc shift in the output voltage ,then you need to apply the required voltage level from an external voltage source to the Vocm pin. It also requires a 0.1uF decoupling capacitor to filter out any high-frequency noise.

    Regards,

    Sid

  • 0 in reply to Sid
    Prodigy 250 points

    Bump, this question. TI must have specs somewhere about this input?

  • 0 in reply to Per-Anders Sjöström
    Genius 4530 points

    Hi peranders,

    Actually Vocm just sets the DC voltage level around which the OUTPUT voltage is centred.

    The peak to peak level of output voltage is the same. Its just that this output voltage is offset by the voltage given to Vocm. This offset voltage should not need any specifications because it mainly depends on what device you are using at the output of OPA1632. You can have the dc offset as 0V, 1V, 5V, 10V ,etc.. as long as it is sustainable by the device to which this output voltage is fed. The peak to peak output voltage is still the same.

    So, I think the specifications are not mentioned because they can be variable depending on the output device.

    Hope this helps.

    Regards,

    Sid